Susceptibility of Enterococcus faecalis and Propionibacterium acnes to antimicrobial photodynamic therapy

Abstract

Bacterial resistance to available antibiotics nowadays is a global threat leading researchers around the world to study new treatment modalities for infections. Antimicrobial photodynamic therapy (aPDT) has been considered an effective and promising therapeutic alternative in this scenario. Briefly, this therapy is based on the activation of a non-toxic photosensitizing agent, known as photosensitizer (PS), by light at a specific wavelength generating cytotoxic singlet oxygen and free radicals. Virtually all studies related to aPDT involve a huge screening to identify ideal PS concentration and light dose combinations, a laborious and time-consuming process that is hardly disclosed in the literature. Herein, we describe an antimicrobial Photodynamic Therapy (aPDT) study against Enterococcus faecalis and Propionibacterium acnes employing methylene blue, chlorin-e6 or curcumin as PS. Similarities and discrepancies between the two bacterial species were pointed out in an attempt to speed up and facilitate futures studies against those clinical relevant strains. Susceptibility tests were performed by the broth microdilution method. Our results demonstrate that aPDT mediated by the three above-mentioned PS was effective in eliminating both gram-positive bacteria, although P. acnes showed remarkably higher susceptibility to aPDT when compared to E. faecalis. PS uptake assays revealed that P. acnes is 80 times more efficient than E. faecalis in internalizing all three PS molecules. Our results evidence that the cell wall structure is not a limiting feature when predicting bacterial susceptibility to aPDT treatment.

Effect of Photodynamic Therapy on Microorganisms Responsible for Dental Caries: A Systematic Review and Meta-Analysis

“…It allows for the deep penetration of light in the biological tissues and expressive quantum yield for singlet oxygen formation [61,62]. The literature has already established the action of PDT mediated by MB, presenting its action against several bacteria associated with oral diseases [63,64]. MB has characteristics that promote good interaction with bacteria such as the positive charge on the molecule and low molecular mass.…”

Potential Role of the Microbiome in Acne: A Comprehensive Review

“…Alternative acne treatments include blue light, ultraviolet (UV) phototherapy, and photodynamic therapy [117,118,119]. These approaches could improve acne by reshaping the skin microbiota and lowering C. acnes counts within the lesions.…”

Antimicrobial Photoinactivation Approach Based on Natural Agents for Control of Bacteria Biofilms in Spacecraft

“…Several studies have verified its photoinactivation ability when activated with the proper wavelengths of light [ 88 ]. CUR-based API could induce significant killing of Gram-positive E. faecalis cells [ 153 , 154 , 155 , 156 ]. Pileggi et al (2013) demonstrated that 10 µM of photoactivated CUR could completely inactivate E. faecalis biofilms after 30 min preincubation and 240-sec irradiation [ 156 ].…”

“…Furthermore, the required illumination doses have to be discussed and compared with general illumination conditions. RF can be excited by blue light and requires from 3 to 400 J/cm 2 according to the data available in the literature (see Table S1 of Supplementary Material ) [ 93 , 94 , 95 , 96 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 117 , 118 , 119 , 120 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 148 , 149 , 150 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 165 , 173 , 175 , 176 , 177 , 178 , 179 , 180 , 181 ,…”